This application is based on Japanese Patent Application No. 2001-001724 filed in Japan on Jan. 9, 2001, the entire content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an optical switch for reflecting or transmitting light by a switching member disposed on an optical path of an optical waveguide, and changing the running direction of light by the moving of the switching member.
2. Description of the Related Art
A conventional optical switch is disclosed, for example, in Japanese Unexamined Patent Publication No. 2000-121967A. In this optical switch, a micro mirror disposed on an optical path of luminous flux emitted from an optical fiber is supported by a movable plate, and the movable plate is moved by applying a voltage to move the micro mirror away from the optical path, so that forwarding and reflecting of light are changed over.
On the other hand, U.S. Pat. No. 5,699,462 discloses an optical switch in which grooves obliquely crossing two intersecting optical waveguides are provided, bubbles are formed in the liquid filling the grooves, and bubbles are heated and moved by a micro heater. In this optical switch, the refractive index of the filling liquid and the refractive index of the optical waveguide are set nearly equal, and therefore when the liquid is placed on the optical path of the optical waveguide, the light goes straightly forward, and when bubbles are placed, the light is reflected and the running direction is changed over.
Recently, the so-called wavelength multiplex communication is developed, in which different pieces of information are put on light (carrier) of different wavelengths, and plural carriers are superposed, so that a large quantity of information can be transmitted by one optical fiber. According to such conventional optical switch, however, the lights multiplexed in wavelength are uniformly reflected or transmitted, and pieces of information put on different carriers cannot be issued separately. Accordingly, information is taken out by filtering by a branching filter, and the optical communication system having the optical switch is complicated in configuration.
Besides, the optical switch disclosed in the above mentioned Japanese Unexamined Patent Publication No. 2000-121967A requires a collimator lens in order to issue the exit light from the optical fiber to the optical fiber by reflecting or transmitting by the micro mirror. The optical switch disclosed in U.S. Pat. No. 5,699,462 requires a micro heater for heating and a mechanism for releasing its heat. As a result, the optical switch is complicated in either case.
It is hence a primary object of the invention to present an optical switch capable of issuing wavelength multiplexed lights separately. It is also an object of the invention to present an optical switch simple in structure.
To achieve the objects, the optical switch reflecting one aspect of the invention is an optical switch for changing over the running direction of the light passing through an optical waveguide between a first direction and a second direction by moving a switching member disposed on an optical path of an optical waveguide, in which the switching member has plural switching positions, and these switching positions selectively guide each of lights of at least two different wavelengths into the first direction or second direction.
According to this configuration, by moving the switching member, the switching positions disposed on the optical path can be changed over, and lights of at least two different wavelengths can be guided selectively into the first direction or second direction. Further, by properly setting the position of the switching member, both switching positions can be kept away from the optical path. Therefore, for example, when the switching member is moved away from the optical path of the optical waveguide, the wavelength multiplexed incident light runs forward straightly, and when the switching member is disposed on the optical path of the optical waveguide, light of one wavelength passes and light of other wavelength is reflected.
Moreover, in the configuration, the switching member may be also configured to move within the groove intersecting with the optical waveguide. The groove may be filled with liquid, and in this case by moving the liquid in the groove by a micro pump coupled to the groove, the switching member may be moved.
Further, in the configuration, each switching position may be an interference filter.
The optical switch reflecting other aspect of the invention comprises a groove intersecting with an optical waveguide and filled with liquid, a switching member movably provided in the groove, and a micro pump coupled to the groove for transferring the liquid in the groove.
According to this configuration, when the micro pump is driven, the liquid in the groove intersecting with the optical waveguide is fed, and the switching member moves in the groove. As a result, when the liquid and optical wave guide, for example, are matched in refractive index, by moving the switching member away from the optical path of the optical waveguide, the wavelength multiplexed incident light runs straightly forward, or by placing the switching member on the optical path of the optical waveguide, the incident light is reflected.
In this configuration, the micro pump may comprise a piezoelectric element, and in this case, by controlling the voltage applied to the piezoelectric element, optical switching operation may be realized.
Further, a plurality of any one of these optical switches may be disposed on a same optical path. In this configuration, wavelength multiplexed light is transmitted to one optical path having n optical switches arranged in series, and a light of a desired wavelength may be guided into a desired output port out of n output ports.